Tunneling-machine



H. R. HUGHES.

TUNNELING MACHINE.

APPLICATION man JUNE 24. I918.

Patented Mar. 9,1920.

I 2 SHEETS-SHEET I- HbwARD R.HUGHES, avwewtoz H. R. HUGHES.

TUNNELING MACHINE.

APPLICATION FILED JUNE 24. 191B.

Patented Mar. 9, 1920.

2 SHEETSSHEET 2- HOYYARD R. HUGHES wvemi oz l I I I I I In HOWARD R.HUGHES, OF HOUSTON, TEXAS.

TUNNELING-MACHINE.

Specification of Letters Patent.

Patented Mar. 9, 1920.

Application filed June 24, 1918. Serial No. 241,459.

To all whom it may concern:

Be it known that- I, HOWARD R. HUGHES, a citizen of the United States,residing at Houston, Harris county, Texas, have invented a certain newand useful Improvement in Tunneling-Machines, of which the following isa full, clear, and exact description, such as will enable others skilledin the art to which it appertains to make and use the same. p I

My invention relates to tunneling machines for drilling in earth or rockand has particular reference to a device for tunneling in a horizontalor approximately horizontal direction underground.

In subterranean mining or in sapping operations in warfare, the commonmethod is to dig the tunnel by hand by means of pick and shovel orsimilar implements and the process is a slow and laborious one.Tunnellng machines have been devised before with the aim in view ofexpediting this operation, but with varying success.

The object ofmy invention is to provide a tunneling device which will belight and" strong in construction and hence easy to transport fromplace. to place, and which will be, at the same time, large enough todig a hole in which a man can enter and operate.

Another object is to devise a novel means for mechanically digging atunnel, which will operate in soft earth or hard rock with efliciency,but which is especially adapted for rock drilling.

Another object is to devise a drilling ma chine which will operate thedrill and which will follow the drill into the hole; and wherein theoperating means will serve both to drive the drill bit and to move thedrilling machine forward behind the bit. 1

Another object is to so arrange the mechanism of the drill operatingmeans that the greater clearness.

operator can regulate the running thereof with a maximum of convenience.

Other objects and advantages of-my invention will more clearly appear inthe description which follows and the same will be indicated with moreparticularity in the claims appended hereto.

In the drawing forming a part of this specification, Figure 1 is a sideview of my invention. Fig. 2 is a similar View showing a different formof drill bit and with certain parts broken away and in section for Fig.,3 is a transverse section on the line 33 of Fig. 1. Fig. 4 is a frontelevation of the bit shown in Fig.

1 the core of the rock being shown between Fig. 9 is a broken detail ofthe rear end of my device showing a means for regulating the operationof certain parts. Fig. 10

shows a side'and end view of my brake band for use in feeding the bit ina longitudinal direction, and Fig. 1'1 is a broken plan view of thedriving gears shown adjacent the line 88 of Fig. 2.

In the different figures of the drawing, wherein like numerals areapplied to like parts throughout the several views, I have shown myimproved device in connection with two different, drill bits. In Fig. 1I have represented the preferred embodiment of drill bit which consistsof a spider 1 having detachably connected thereon a plurality offorwardly projecting supports 2 upon which the cutting rollers 5 aremounted. These cutters are frusto-conical rollers, toothed on theirperipheries as shown, the rollers not being considered as new. Theforward end of each of the supports 2isslotted as shown at 3 to providea mounting for the cut-ting rollers 5 which are rotatable upon thespindles 4: fitted rig-idly within the supports 2. Each of the supportsfurnishes a mounting for a plurality, preferably two, of these rollingcutters and it is contemplated thatone of the cutters shall be in clinedinwardly toward the center of the head and the other inclined outwardlytoward the outer portion of the bore hole for the purpose of obtainingclearance for the drill on each side of the support as shown '2 in Figs.4 and 6. The cutters are set into the support 3 so as to partially housethe cutters and also so that the support 2 will furnish a supportingmeans for the outer end of the pins 4 upon which the cutting rollersrotate.

Concentric with the spider 1 and forming.

.which the main central drill bit 9 is attached. This central bit 9 is acone bit and is particularly disclosed in my prior Patent No. 930,759granted to me on August 10th, 1909. It has a flattened cylindrical headprovided with a V shaped slot in one end thereof. Upon the flattenedfaces of said slot are mounted the cutting cones 10. The tunneling drillthus provided will, as is obvious from the drawing, drill a centralcyllndrical hole and an outer annular hole spaced away from andconcentric with the inner hole.

In order to provide against the contingency of the wearing away of thecutters 5,

thereby reducing the gage ofthe hole being drilled, I have provided, onoutwardly projecting arms on the spider 1, a slidable block 11, on theouter end of which is mounted a reaming roller 12. The sliding block 11is held in place upon the spider '1 by means of an outer housing 13,shown particularly in Figs. land 5. This housing is bolted to orintegral with the spider 1. The block 11 slides within the housing 13and is actuated therein by means of a worm gear 15 which meshes with therack 15 upon the slidable block. The worm gear 15 is secured upon arotatable pin 16 which is supported at one end in the housin 13 and atthe other end in the central hub of the spider 1. On the inner end ofsaid pin 16 is fastened a beveled gear 17 meshing with the rotatableannular gear 18 which bears upon the forward enlarged end 20 of an outeroperating sleeve 21. These outer slidable blocks 11, with the reamingrollers 12 mounted thereon, are three in number in the embodiment whichI have shown, although it is obvious that any different number ofreaming rollers-may be provided. When it is desired to enlarge the holesomewhat or to take up. the wear occasioned by the operation of theserollers upon the sides of the hole theblocks 11 may be forced outwardlyby means of the worm 15 into firmer contact with the side of the hole ina manner which will be later described.

In Figs. 2 and 6 I have shown a bit similar to the one disclosed in Fig.1 but which is provided with an extra set of radially mounted diskcutters for the purpose of cutting away the core which would otherwiseremain between the inner drill 9 and the outer drills 5. Inaccomplishing this purpose the forwardly projecting supports 2 aresomewhat shortened and a supporting spindle 22 ismounted in a recess inthe inner side of said supports, said spindle being mounted at theopposite end within a recess in the hub 7 of the spider .1. Upon the]three spindles 22 are mounted a series of separate rotating disks 23.These disks are of larger diameter toward the outer' end of the spindleand decrease regularly in size toward the central bit 9. On examinationof Figs. 2 and 6 it will be noted that these three radial cutters. justdescribed, each comprise a conical cutter or group of cutters which arewell adapted to roll upon the core left by the principal cutters 5 and 9and to disintegrate the material by means of the toothed surfaces of thedisks rolling upon and breaking Ifip the material at the forward: end ofthe ole.

The means by which the drill is rotated will now be described. Withparticular reference to Fig. 2, it will be noted that the main bit 9 ismounted within the central sleeve or drill stem 8. This sleeve extendsbackwardly within the hole for some distance and is externally threadedtoward the rear end thereof as shown at 24 for a purpose which willlater appear. This sleeve or drill stem 8 is rotatable within the hub 7and the outer sleeve 21 and is fitted with bushings 25 and 26 thereon.Toward the threaded endof the drill stem is fitted an outer nut 27 inthe form of a sleeve, which nut is threaded upon the portion 24 of thestem. The nut 27 ordinarily rotates with the drill stem within thebearings 28 and 29 of the main framework 30.

The framework constitutes a mounting for the rotatable parts, and forthe operating means, and consists of a series of four or more transverseframe members 31 which are somewhat rectangular in shape as shownparticularly in Figs. 3 and 5. Connecting these rectangular members 31are longitudinal cross pieces 32. This framework thus constructed issupported adjustably within the tunnel drilled by the bit by means ofslidable bolts or pins 34 carrying on their outer ends the toothedblocks 35 which are .adapted to be projected into rigid contact with theside. of the tunnel and thus retain the frame in adjusted position. 34are supported by the frame members 31 within the housing 36 providedthereon. Toward the inner end of each of the pins is mounted adisk-shaped worm gear 37 adapted to mesh with a cooperating gear 38 (seeFig. 3) upon the shaft 39 and within the framework 31 as previouslydescribed. Toward the rear endof each of the shafts 39 is provided ahand wheel 39' with which the same may be rotated to advance or withdrawthe clamping bolts 34 in an obvious manner.

It will be noted, as shown particularly in Fig. 2 that the shafts 39,both at the upper and lower sides of the frame, are provided withclutches 40 and 41 by means of which either of the bolts 34 may beoperated as desired. When the shaft 39, which is slidablelongitudinally, is moved forwardly, the clutch 41 will be forced intomesh with a co6perating part 42 of said clutch which is connected withthe worm gear 38 previviously described. When the shaft 39 is movedrearwardly the, clutch 41 is thrown ,out and the clutch 40 is forcedinto cooperative engagement with the clutch member 43 connected with theworm gear The pins threaded upon the bolt 34. Thus the turning of thegear 37 will force the bolt 34 out- Wardly or inwardly according to thedirection of rotation of said hand Wheel 39.

The framework is also further braced and held in rigid position by meansof the supporting bolts-44 shown especially in Figs. 2 and 5. Thesebolts are hinged at their inner ends to the rear supporting member 31 ofthe frame and extend backwardly and upwardly into contact with the sideof the bore hole. These bolts consist of two 00- operating partsconnected by the threaded expanding member 45 by means of which they arelengthened or shortened in the usual manner, so as to clamp the frame inrigid position. The center bit 9 has been described as rotated by theinner revoluble sleeve or stem 8. The outer drill members 5 and also therollers 23 are given their rotative movement through the outer sleeve21, the forward head 20 of which is bolted securely to the spider 1, bymeans of the bolts 46 or other equivalent means. The sleeve 21 extendsbackwardly outside the stem 8 somewhat more than half the length of saidstem and llLS a bearing 47 in the framework. The bearing 47 is providedwith a bushing 48 and within the bushing is a rotating bear ing sleeve49, held rotatable with the sleeve 21 by the key 50.- On the rear end ofthe sleeve 21 is threaded a drive gear 51, said gear being further fixedon said sleeve by means of the key 52.

Spaced rearwardly from the gear 51 the inner stem 8 is provided with theexternal drive gear 53, keyed thereto in an obvious manner as shown inFig. 2. The stem 8, at

a point between the gear 53 and the rear end of the sleeve 21, isprovided with an outwardly flaring integral flange 54. The gear 51 uponthe sleeve 21 has an integral hub member 55 which is extended rearwardlyand has at the end thereof an inwardly extending flange 56. Between theflanges 54 and 56 is a non-friction bearing, a similar bearing 57 beingprovided on the opposite side of the flange 54 and between that flangeand the sleeve 21. This provision allows the two drill sleeves or stemsto rotate independently and yet causes them to advance or recedesimultaneously as will be more fully explained later.

I have shown my machine as actuated by means of an electric motor 58seated toward thefront of the framework 30, upon a shelf 58 thereon. Themotor is connected to the parallel drive shaft 60 through connectinggears 69, on the motor shaft, and 59, on the drive Shaft. Over the Shaft60 1s fitted a longitudinally slidable drive sleeve 61, said sleevebeing also rotatable on the shaft 60. At the forward end of the sleeve61 is a clutch member 62 adapted to co5perate with the clutch member 63,fixed rigidly upon the shaft 60. It will thus be seen that when thesleeve 61 is moved on the shaft 60 to its forward position inco5perative relationship with the clutch 63 the said sleeve will rotatewith the drive shaft 60. Referring to Fig. 9 it will be seen that therear end of the sleeve 61 is provided with a circumferential slot 64into which is fitted a projection on the arm 65, said arm beingconnected by means of a shaft 66 to a hand lever 67 pivoted at 68 to theforward frame member. Thus, the movement of the lever 67 on its pivot 68will serve to slidefthe sleeve 61 longitudinally upon the shaft 60 forthe 35 purpose of throwing it into or out of engagement with the clutch63.

Keyed slidably upon the outer sleeve 61 are thetwo gears 70' and 71adapted to engage with the aforementioned gears 51 and 53 respectively.By reference to Fig. 11, it will be noted that when the outer sleeve 61in its forward position meshes with the clutch 63 on the drive shaft,the said outer sleeve is rotated. This rotation is communicated throughthe" gear 70 to the gear 51 upon the sleeve 21. The stem 8 is actuatedthrough the gear 71 which meshes with the gear 53 upon said stem. Itwill also be noted, because of the relative size of the actuating gearsupon these two parallel sleeves, that the outer drill sleeve 21 will bedriven at a lower speed than the inner drill sleeve 8 and it will beobvious that such a differential rotation of the two drilling parts isnecessary, due to the fact that the outer cutters 5 are rotated througha longer path than is the drill 9. I

' In order that the reaming cutters 12 may be advanced or withdrawn toorfrom ad justed position while the drill is being operated I havearranged the following mechanism: Mounted in the two rotating bearingsleeves 49, shown in Fig. 2, is a longitudinally extending shaft 72,which is supported at its forward end in the head 20 of the outer sleeve21. At the forward end of this shaft 72, and within a recess providedtherefor in the head. 20, is fixed a gear 73, the teeth of which areadapted to mesh with internal gear teeth 19 upon the gear ring 18,previouslv described. At the rear end of the shaft 72 is fixed a similargear 74, said gear fitting'within a recess provided therefor interiorlyof the gear 51 and its rearwardly extending hub 55. Mounted rotatablyupon the rearwardly extending hub 55 is an annular gear ring 75. Saidgear .75 is provided centrally thereon with external gear teeth 76 and,upon the forward end of said ring, are interior gear teeth 77 adapted tomesh with the teeth upon the gear 74.

Referring now particularly to Figs. 1 and 5, I have provided a shaft 78which is rotatable within the framework 31 and which has, at itsrearward end, the hand wheel 79 operated by means of the crank handle80. Outside of this hand wheel 79, is the brake band 81 having a brakehandle 82 for tightening same in an obvious manner. The gear ring 75 isinclosed in the casing 84 for protection and adjacent the gear ring'75,and upon the shaft 78, is the gear 83 .(see Figs. 8 and 11) adapted tomesh with the teeth 76 upon the said gear ring through an opening 85 inthe casing 84. Thus it will be obvious that the rotation of the shaft 78will be communicated by means of the gear ring, 75 and the ear 74 to theshaft 72 and through this shaf and the connecting gears at the forwardend thereof, will act to advance or withdraw the slidable block 11.While the drills are operating, the sleeve 21 and the gear 51 togetherwith the shaft 72 are revolving around the central stem 8. The housing84 of the gear ring 7 5 is non-rotatable (being held so by shaft 78, seeFig. 8) but it will be noted that, as the shaft 72 and the gear 74describe a planetary revolution inside the ear ring 75, the meshing ofthe gear 74 with t he teeth 77 of the gear ring will cause the gear ringto rotate. The rotation of the gear ring 75 will be communicated to theshaft 78 through the gear 83. Hence as the drill operates in normalmanner the shaft 72 does not rotate but describes a planetary revolutionaround the drill stem. Its planetary revolution rotates the gear ring 75and through that gear, the shaft 78, causing the hand wheel 79 thereonto-spin or rotate constantly. When the brake band 81 is tightened on thesaid hand wheel, the gear 83 and the gear ring 75 will be slowed up orentirely stopped as long as the brake is applied. Hence as the planetarymovement of the gear 74 inside the gear ring 75 continues, the gear 74will be also caused to rotate in its bearings and this rotation will becommunicated' through shaft 72 to the gears 73,

18, 17 and 15 to cause the block 11 and roller 12 to be advanced. Assoon as the roller 12 is in its desired position the brake is releasedand the hand wheel 79 will rotate as before. It is apparent, of course,that when the drill is not operating the rollers 12 may be advanced orwithdrawn by the release of the brake 81 and the manual operation of thehand wheel 79.

\Vhen the drill stem 8 is rotating, the sleeve or nut 27 will normallyrotate with it and no forwardfeed of the drill stem will result.Provision is made, however, so that the nut 27 may be slowed up inrotation or entirely stopped as desired. To obtain this result, the nutis provided with a central enlarge- (see Figs. 10 and 1). Thus when itis de-' sired to feed the stem forwardly the brake band is tightened andthe rotation of the nut 86 is slowed up or stopped. The continuedrotation of the drill stem 8 will then cause it to feed forwardly in thenut and thus advance the bit as desired. When-the bit is to bewithdrawn, the motor is reversed.

The outer surface of the hub 86 of the nut 27 is toothed at 94 toreceive a sprocket chain 95, (shown in Figs. 1 and 9 but removed in Fig.2). This sprocket chain connects the nut 27 with the gear 96 looselymounted on shaft 69. This gear 96 may be clutched into rotation with theshaft 60 my means of a clutch 97 keyed slidably on the shaft 60 andoperated to and from engagement with gear 96 by means of the lever 90.By means of this arrangement the nut 27 may be operated to advance orwithdraw the drill stem when the rest of the machine is out of gear andnot operating.

1 'When the drill stem is fed forward or withdrawn it is desirable thatthe sleeve 21 and the operating gears shown in'Fig. 11 movelongitudinally with the drill stem. It is apparent that the flange 54 onthe stem 8 will, because of its connection with the gear 51 and its hub55, cause the sleeve 21 tomove forwardly or backwardly with the drillstem. The movement of the gears 51 and 53 will carry with them thecasing 84 which is rovided with a laterally extending arm 98.

he gears 7 0 and 71 are keyed slidably in the groove 100 on the drivesleeve 61 and are connected by a hub 101 having a circumferential groove99 to receive the outer end of the arm 98. Thus the movement of thegears 51 and 53 longitudinally will carry with them the gears 70 and 71on the parallel shaft 61.

When the drill has drive-n forwardly t0 the position shown in Figs. 1and 2 where further advance will act to screw the stem 8 out of the nut27, the drill is stopped and the supporting frame 30 is brought forwardto a new position for further drilling. To advance the supporting framethe hand wheel 79 is rotated to advance the rollers 12 sufficiently tosecure thezbit firmly in the hole. The'rollers 12 thus act as a clampingmeans to secure the drill head against movement of any kind. I

To support the frame of the machine v with it the frame and the while itis moved in the hole, I have devised two roller supports 102, whichordinarily rest on the bottom of the tunnel. The supports 102 aremounted rotatably in a frame 103 ivoted at 104 to the frame members 32.he upper end of the frame 103 is sector shaped and toothed forcooperation with a worm gear 105 on a shaft 106 mounted in the frame.The worm gears 105 are rotatable on the shaft 106 but may be thrown intoor out of gear with said shaft by. 'a clutch 108 on the shaft which isarranged to mesh with a cooperating clutch member,

109 onthe gears 105 when the shaft is moved longitudinally. The shaft106 has a hand wheel 110 thereon. By reference to Fig. 1 of the drawing,it will be seen that when the hand wheel 110 is rotated in the properdirection one of the gears 105 will operate to force one of the wheels102 downwardly into supporting engagement with the bottom of the tunnel.The shaft 106 is then shifted longitudinally to throw the other clutch108, 109 into mesh and the shaft may then be rotated to force the othersupporting wheel 102 firmly against the bottom of the tunnel. In thisposition of the wheels 102, the frame 30 will be supported by saidwheels and the bolts 34 may be withdrawn and the brace bolts 44: may beloosened and swung back againts the frame. The frame is then ready to bemoved forwardly.

To move the frame forwardly the drill is thrown out of gear with thedriving mechanism and the motor is operated in reverse direction throughmeans of a controller 113 on the rear end of the machine. The lever 90is then operated to connect the drive shaft 60 through the sprocketchain 95 to the nut 27, rotating said nut so as to feed the sameforwardly on the drill stem 8. The forward movement of the nut 27 willcarry machine supported thereon, the whole machine resting on thewheels'102. When the frame is moved to thedesired point the motor isstopped, the bolts 34 and the jaws 35 thereon are moved out, one by one,into supporting contact with the sides of the tpnnel. The bracing bolts44: are secured in place and the wheels 102 are then released and thedevice is again ready for drilling.

In the use of the bit represented in Fig. 1 in which an annular core isleft in the drilling operation, it is obvious that the bit must bestopped periodically and the core removed. To do this the bit iswithdrawn from contact with the front of the bore hole and the core isbroken up so that it may be withdrawn. The core of the rock at theforward part of the hole may be removed by any suitable means, ahydraulic cartridge placed in the annular hole outside of the core maybeu'sed to crush the core or an explosive charge may be placed in thecentral bore hole and detonated. The broken fragments of the core arethen removed by a workman from the passage allowed at one side of theframework, as shown particularly at the left of F ig. 3. A platform orwalking board 107 is provided on the side of the frame for this purpose.In the use of the form of bit shown in Fig. 2 the detritus will beremoved in the same manner.

The numeral .111 designates a chuck of ordinary construction at the rearend of the hollow sleeve 8. This chuck is designed to grip a pipe ofsmaller "diameter should it be desired to insert such a pipe through thesleeve 8 for any purpose. I 1

Having thus described my invention th operation and advantages of whichwill be clear without further description what I claim as new and desireto protect by Letters Patent'is:

1. A machine for tunneling comprising a central drill stem, a bitthereon, an outer drill stem, a bit thereon, reaming rollers rotatingwith said outer drill stem, means to operate both drill stemssimultaneously and means on said outer drill stem to ad- Vance andwithdraw said reaming rollers while said drills are being operated.

2. A machine for tunneling comprising a central drill, an outer drill,reaming rollers mounted adjustably on said outer drill,

means to drive said drills at different speeds and means to adjust saidrollers while said drills are being operated.

3. A machine for tunneling, comprising a central drill, an outer drill,separate means for operating each drill, reaming cutters on said outerdrill, said cutters being mounted on a slidable block, a rack on saidblock, a worm gear engaging said rack and means to operate said wormgear while said drills are operating.

4. A machine for tunneling, comprising a central drill, an outer drill,separate means a for operating each drill, reaming cutters on said outerdrill, said cutters being mounted on slidable blocks, a rack on each ofsaid blocks, a worm gear engaging said racks and means to operate saidworm gears while said drills are operating, said means comprising alongitudinal. shaft, adapted to revolve around said central drill andoperating means, connecting gears between said shaft and said worm gearand means to rotate said shaft.

5. In a tunneling machine, a drill, laterally adjustable reaming cuttersthereon,

means to advance said cutters to clamp said bit securely in the tunnel,a longitudinally adjustable frame, operating means for said drillmounted in said frame, means actuated by said operating means to movesaid operating means and frame forward or backward in the hole when saidbit is clamped in rigid position.

6. In a tunneling machine, a supporting frame, a central drill stemrotatable in said frame, an outer drill stem, means to rotate said stemsat different speeds and means operated by said rotating means to advancesaid stems as desired independently of said frame.

7. In a tunneling machine, a supporting frame, an outer drill stemrotatable in the forward part of said frame, an inner drill stemrotatable within said outer stem and in said frame, means to feed saidinner stem forwardly or backwardly and means on said inner stem to causesaid outer stem to move longitudinally simultaneously with said innorstem.

8. In a tunneling machine, a supporting frame, two concentric drillstems mounted in said frame, means to operate said drill stems atdifferent speeds and means to feed said stems longitudinally of saidframe simultaneously at will.

9. In a tunneling machine, a supporting frame, two concentric drillstems rotatable in said frame, separate operating gears for each stem, anut on the rear end of the said inner stem, an outstanding flange onsaid inner stem, said flange serving to move said outer stemlongitudinally in synchronism with said inner stem and means foroperating said nut to cause a longitudinal movement of said inner stem.

10. In a tunneling machine, a supporting frame, .means to temporarilysupport said frame during movement comprising sector shaped blockspivoted in said frame, a roller mounted in an arm on each of saidblocks, a rack on the curved edge of said blocks, a

worm gear mounted on a rodin said frame and cooperatlng wlth said rackto ra1se or lower said roller.

, 11. In amachine for tunneling, a compound drill comprising a centraldrill and an outer core drill, reamers on said core drill and means .onsaid core drill and rotatable therewith to adjust the position of saidreamers While the drills are operating.

12. In a machine for tunneling, a compound drill comprising a centraldrill and an outer core drill, reamers on said core drill, means toadjust the position of said reamers on said drill when the drills areoperating, shaft geared to said reamers, and adapted to be operatedthrough means of a brake and drum. 7

13. In a drill for tunneling, reaming and clamping rollers capable ofadjustment laterally of said drill, and means to adjust said reamerswhile said drill is operating. 1 1. In a drill for tunneling, reamingand clamping rollers adjustable laterally of said drill, said rollersbeing mounted on a block, a rack on said block, a worm gear cooperatingwith said rack and means at the rear of said drill for operating saidworm gear.

15. In a tunneling machine, a supporting frame, a drill stem mountedtherein, a drill bit on said stem, means comprising reaming rollers onsaid bit to clamp said stem rigidly in the hole, and means to advancesaid supporting frame along said drill stem.

In testimony whereof I hereunto afix my signature this 14 day of June,1918.

HO WARD R. HUGHES.

said means, comprising a rotating,

